I am planning to install laminate flooring in a room the main level of a concrete slab. After peeling off the original carpet, there appears to be a few inches of uneven concrete that runs along the drywall covering the exterior walls (but not the interior walls).



There is around an inch or two of blue polystyrene with a plastic moisture barrier between the "outer" concrete and "inner" concrete. The "inner" concrete appears to have been levelled (1/8-inch maximum imperfections), but approximately 1/2 inch lower than the "outer" concrete.

What should I do to raise the "inner" concrete floor to achieve a constant level throughout the room? Would I need to use levelling compound on the few inches of "outer" concrete?

Unrelated to the topic of flooring: Is the protruding "outer" concrete part of the concrete slab foundation?

Thank you in advance!

 

I'm not sure how they do things in Vancouver, but it looks as if the outer "rim" is made of concrete block, and the center was poured later, not very well, I might add. You must level the floor in order to install any laminate, but how many square feet are you talking about? Is the main floor lower than the strip?

 

I plan to lay laminate flooring in just one room, so around 100 square feet. The main floor is approximately 1/2 inch lower than the strip. Would using 1/2 inch extruded polystyrene be okay to raise the "inner" level?